Novel Method for Ultrasound-Derived Fat Fraction Using an Integrated Phantom

The purpose of this study was to demonstrate the clinical feasibility of an integrated reference phantom method for quantitative ultrasound by creating an ultrasound-derived fat fraction (UDFF) tool. This tool was evaluated with respect to its diagnostic performance as a biomarker for assessing histologic hepatic steatosis and its agreement with the magnetic resonance imaging (MRI) proton density fat fraction (PDFF).

Adults (n = 101) with known or suspected nonalcoholic fatty liver disease consented to participate in this prospective cross-sectional study. All patients underwent MRI-PDFF and ultrasound scans, whereas 90 underwent liver biopsy. A linear least-squares analysis used the attenuation coefficient and backscatter coefficient to create the UDFF model for predicting MRI-PDFF.

The area under the receiver operating characteristic curve values were 0.94 (95% confidence interval [CI], 0.85-0.98) for histologic steatosis grade 0 (n = 6) versus 1 or higher (n = 84), 0.88 (95% CI, 0.8-0.94) for grade 1 or lower (n = 45) versus 2 or higher (n = 45), and 0.83 (95% CI, 0.73-0.9) for grade 2 or lower (n = 78) versus 3 (n = 12). The Pearson correlation coefficient between UDFF and PDFF was ρ = 0.87 with 95% limits of agreement of ±8.5%. Additionally, the diagnosis of steatosis, defined as MRI-PDFF higher than 5% and 10%, had area under the receiver operating characteristic curve values of 0.97 (95% CI, 0.93-0.99) and 0.95 (95% CI, 0.9-0.98), respectively. The body mass index was not correlated with either UDFF or PDFF.

An on-system, integrated UDFF tool provides a simple, noninvasive, accessible, low-cost, and commercially viable clinical tool for quantifying the hepatic fat fraction with a high degree of agreement with histologic biopsy or the MRI-PDFF biomarker.